Half-century anniversaries are special, whether they be the golden wedding anniversary or a retrospective on a world event, a work, or a life. This volume began with a desire to have a series of sessions at the Kalamazoo International Congress on Medieval Studies and at the Leeds International Medieval Congress in 2012 to celebrate the semicentennial of Lynn White Jr.’s Medieval Technology and Social Change (Oxford University Press, 1962; hereafter MTSC). It was hard to find people to speak. Some thought that the idea had merit but had nothing to contribute; some asked whether there was anything more to say on the topic; no one, at least, said that it was a bad idea. Ultimately, many expressed some concern that it was so difficult to find people to speak on what it seemed should be a notable anniversary. The essays in this volume may go some way to explain that difficulty.